ABSTRACT The green apple aphid, Aphis pomi De Geer (Hemiptera: Aphididae) is a major pest of apple, with early‐season infestations mainly driven by the success of overwintered eggs. To characterize its overwintering biology, a 2‐year study was conducted to quantify the timing and pattern of oviposition, egg distribution along shoots, overwintering survival, and hatch dynamics. Oviposition began in early October and lasted 11–12 weeks, peaking between late October and mid‐November. Cumulative egg numbers averaged (mean ± SE) 384.96 ± 15.85 per 30‐cm shoot on bearing plants in 2022, and 453.66 ± 16.49 on bearing plants and 461.84 ± 14.33 on non‐bearing plants in 2023. During the early oviposition phase, eggs were strongly concentrated in the second to fifth 10‐cm shoot segments. However, this spatial gradient weakened over time, with later‐laid eggs more evenly dispersed along the shoot. Three overwintering conditions were compared: intact shoots on trees, excised shoots placed on the ground, and shoots stored under laboratory conditions. Egg survival was highest in the lab (63.6% ± 2.72%), moderate on intact shoots (42.6%–49.6%), and lowest on ground‐excised shoots (23.9%–33.4%). Kaplan–Meier survival analysis indicated a 73% higher hazard of egg mortality in ground shoots compared to intact ones. Egg hatch began in early March and was complete by early April, with median hatch dates around March 20–21 (green tip to half‐inch green tip). Cumulative hatch emerged as a more sensitive parameter than hatch timing alone for detecting treatment effects. These findings establish precise phenological benchmarks and show that oviposition behavior and overwintering success are influenced by shoot microhabitat and condition. This study provides the first large‐scale, data‐driven analysis of A. pomi overwintering and offers key parameters for temperature‐based forecasting and integrated aphid management in apple orchards.
Shah et al. (Tue,) studied this question.